Fix libgcrypt build for powerpcspe

[jhibbits]

Summary

powerpcspe build of security/libgcrypt fails with missing asm-syntax.h
file. Simply add the check for powerpcspe- and powerpc- to the same line as
netbsd and openbsd, as we should be doing the same thing anyway even for 32-bit
powerpc.

Test Plan

compiled for both powerpc and powerpcspe